The letters MV represent Moped Vollnabenbremsen, whicht means the moped has brakes over the full hub.
The bronze coloured MV 50 was only released in the Netherlands (1972) on the occassion of the 25 year Stokvis distributor celebrations. Before this event, this colour wasn't a big success for Puch. Only a few dozens or so were actually sold. It is unknown if there is still an original moped from this series. At the same time the bronze coloured moped (with 3 gear footclutch) )was released, Gelijktijdig met het uitgeven van deze bronskleurige MV (alleen verkrijgbaar met 3 voetversnelling), a lime coloured MV50 was released having the same combination of colours with black. This too wasn't a success story, although more mopeds in this colour scheme were sold than the bronze coloured one.
During 1978, when the VS50 and MV50 Puch models were "finished", Puch tried to stimulate sales one last time by releasing the Crazy Horse model. The Crazy Horse model is actually the same as the lime and bronze coloured MV50s from 1972, but now in the colour combination metallic silver/black. The onlyn differnece is that the chain casing was black as well. One other difference is the specially designed Crazy Horse tank sticker.
In 1973 PUch released the M 50 Skyhawk, a "Belly Slider" model with buddyseat and a headlight with en een koplamp met headlight brackets. In 1975, a real "Belly Slider" was released and named Grand Prix. Sales were not very good and the model was removed from production a year later. Some years later this moped was released again, but now named Monza. In 1981 production seized due to and ever decrease demand. Many of these Puchs have spent a lot of time at the dealerships until they were eventually sold. The main reasons were that cars became more affordable and moped drivers were obligated to wear a safety helmet.
Source: Berrie van Mier, Infonu.nl